1. Field of the Invention
The present invention relates to an electromagnetic active engine mount apparatus, and more particularly, to an electromagnetic active engine mount apparatus, in which a sub-channel through which working fluid flows is formed in the central portion of an electromagnetic drive so as to cool heat generated from a coil of a solenoid section of the electromagnetic drive by repetitive operation of a vibrating member, thereby inhibiting the heat generated from the coil to thus protect various components formed of rubber from thermal damage, and providing improvement of its durability, reduction of its size, and simplification of its structure.
2. Description of Related Art
The engine of a vehicle may be regarded as a kind of vibration generating source. Thus, when the engine is mounted on a body of the vehicle, a medium called an engine mount is used, thereby preventing vibration generated from the engine and its resultant noise from being transmitted to the vehicle body.
Generally, in the case of small gasoline engine vehicles, a bush-type mount apparatus formed of rubber has been mainly used. In the case of large gasoline engine vehicles and diesel engine vehicles, a hydraulic type engine mount apparatus in which fluid is encapsulated has been used. However, this passive engine mount apparatus cannot block the vibration and noise within all the ranges including a variable operation region from the viewpoint of its structure.
The vibration generated from the engine is varied in idling, low-speed running, and high-speed running. As such, the engine mount apparatus requires different levels of dynamic stiffness in the idling and low-speed running and the high-speed running. In detail, low dynamic stiffness is required in the idling and low-speed running, whereas high dynamic stiffness is required in the high-speed running. In connection with a frequency of the vibration generated from the engine, the vibration can be divided into three regions: a shaking region where low-frequency and high-amplitude vibration occurs, an idle region where middle-frequency and middle-amplitude vibration occurs, and a booming region where high-frequency and low-amplitude vibration occurs. In order to produce a more excellent vibration damping effect, the engine mount apparatus must have different dynamic stiffness according to each region.
However, the aforementioned bush-type or hydraulic-type engine mount apparatus cannot have a vibration damping function for the viewpoint of its structure in all these variable regions. Thus, a recent tendency shows that an active engine mount apparatus is developed so as to be able to control the vibration of the engine in all the variable regions.
Generally, the active engine mount apparatus is configured to reduce the vibration of the engine by mounting a separate vibrating member on the liquid-filled engine mount apparatus and thus actively controlling the vibrating member so as to be vibrated according to a vibration state of the engine. The active engine mount apparatus can be classified as an electromagnetic type, a pneumatic type, etc. according to a mode of operating the vibrating member.
FIG. 1 is a schematic cross-sectional view illustrating the structure of a conventional electromagnet active engine mount apparatus.
As illustrated in FIG. 1, the electromagnet active engine mount apparatus is configured so that a center bolt 11 for coupling with an engine is inserted and coupled into and to the central portion of a main rubber 10. The main rubber 10 is coupled on an upper side of a hollow main pipe 20 by, for instance, curing bonding, and is adhered with a diaphragm 30 on an upper circumference thereof. At this time, an orifice section 50 and a vibrating member 60 are air-tightly coupled on a lower side of the main pipe 20, thereby defining a damping chamber 40 such that a working fluid is encapsulated in an inner space defined by the main rubber 10, diaphragm 30 and main pipe 20. The damping chamber 40 is partitioned into a main liquid chamber 41 and an auxiliary liquid chamber 42 by the orifice section 50 and the vibrating member 60. The main and auxiliary liquid chambers 41 and 42 communicate with each other through an orifice channel 51 formed in the orifice section 50.
Generally, the vibrating member 60 is composed of a vibrating plate 61 and a vibrating rubber 62. The vibrating plate 61 is coupled to the orifice section 50 through the vibrating rubber 62, and is vibrated by an electromagnetic drive 70 mounted at a lower portion thereof.
The electromagnetic drive 70 is mounted below the vibrating member 60 and the orifice section 50, and includes a ring-shaped solenoid 74 generating an electromagnetic force, an armature 75 connected to the vibrating member 60 and moving up and down by means of the solenoid 74, and a case 76 enclosing the armature 75. Here, the solenoid 74 includes a coil 71 wound in a ring shape, a yoke 72 enclosing the outside of the coil 71, and a core 73 repeatedly attaching and detaching the armature 75 by means of the electromagnetic force.
With this configuration, when electric current flows through the coil 71, the armature 75 is repeatedly attached to and detached from the core 73 while moving up and down. Simultaneously, the vibrating plate 61 coupled to the armature 75 also repeatedly moves up and down to generate vibration. The vibration of the vibrating plate 61 is transmitted to the working fluid in the main liquid chamber 41. Owing to this transmission of the vibration of the vibrating plate 61, the vibration transmitted from the engine is reduced.
More specifically, a separate controller controls the solenoid 74 according to the vibration state of the engine to generate a waveform having the same phase as that of the vibration of the engine so as to offset the vibration of the engine. At this time, a filtering plate 80, which has a through-hole 81 in the central portion thereof above the vibrating plate 61, is mounted on the orifice section 50, so that the vibration created by the vibrating plate 61 is transmitted to the main liquid chamber 41 through the through-hole 81 of the filtering plate 80.
Meanwhile, this vibration damping effect caused by the vibrating plate 61 is mainly used to reduce the high-frequency vibration of the engine. In the case of the low-frequency vibration of the engine, as in the ordinary liquid-filled engine mount apparatus, the vibration is reduced by inertial resistance of the working fluid flowing between the main and auxiliary liquid chambers 41 and 42 through the orifice section 50.
Accordingly, this electromagnetic active engine mount apparatus can reduce the vibration of the engine in both the high and low frequency ranges. However, from the viewpoint of its structure, when the vibrating plate 61 is repeatedly operated, heat is generated from the coil 71 of the solenoid 74. Due to this heat generating phenomenon, various rubber components of the engine mount apparatus may be damaged by the heat. As a result, the engine mount apparatus cannot smoothly perform the function of reducing the vibration of the engine, and thus must be frequently replaced by periods.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.